(1) Field of the Invention
The present invention relates to a gel of a microbially-produced cellulose, in which an animal cell adhesive protein is bonded to said cellulose or said cellulose is chemically modified.
This gel is valuable as a carrier for mass culture of animal cells or as a medical vulnerary cover. Especially, a complex comprising an animal cell bonded to or adsorbed in this gel is Very valuable as a medical vulnerary cover.
(2) Description of the Related Art
The mass culture method using a carrier to which an animal cell is bonded is widely adopted.
As the material for the carrier, there can be mentioned plastics and glass for a sheet or plate carrier, crosslinked gelatin (Gell-Beads supplied by KC Biological Co., U.S.A.), charged group-added polyacrylamide (Biocarrier supplied by Bio-Rad Co., U.S.A.), polystyrene (Biosilon supplied by Nunc Co., Denmark), dextran (Superbeads supplied by Flow Labs Co., U.S.A.), cellulose granule (DE-52 supplied by Whatman Co., Great Britain) and collagen-coated dextran (Cytodex supplied by Pharmacia Co., Sweden) for a bead carrier, and cellulose acetate (supplied by Amicon Co., U.S.A.) for a hollow fiber carrier.
A protecting material for protecting an externally wounded or burnt skin at an accident or disaster, promoting regrowth of the epidermis, and healing the wound is called "vulnerary cover" or "artificial skin" (hereinafter referred to as "vulnerary cover").
Gauze has heretofore been used most widely as the vulnerary cover, but recently, lyophilized pig skin (LPS) having superior characteristics to gauze has been used. This is a living body material and in appearance resembles human skin. This material is soft and has a good adhesion to a wound and is superior in that it promotes regrowth of the skin.
Furthermore, a vulnerary cover composed of collagen has recently been marketed. This vulnerary cover is in the form of a non-woven fabric or film or is complexed with a silicone film, and is characterized in that it has no antigenic property and sterilization is possible.
Moreover, a complex of a polyamino acid film and a synthetic polymer film has been proposed as a vulnerary cover. This vulnerary cover is characterized in that it is not decomposed by a protease.
In addition, there is known a plasma film or fibrin film prepared from human blood. This film has an excellent absorbing property and is not irritating to the human body.
Still further, a vulnerary cover utilizing a film of a microbially-produced cellulose, which is different from an amino acid polymer or a protein, is proposed in British Patent No. 2131,701.
Materials customarily used for carriers for mass culture of animal cells have problems in that the adhesion of animal cells and the propagation quantity of animal cells are insufficient. Moreover, a material capable of providing a sheet-shaped or plate-shaped carrier having an excellent softness and the like has not been developed.
Furthermore, materials heretofore used for vulnerary covers involve the following problems. A vulnerary cover formed of lyophilized pig skin or collagen is readily decomposed by a protease and is fused to cause contamination. Accordingly, it is necessary to frequently renew a vulnerary cover. A film of a polyamino acid is not decomposed by a protease, but the film must be supported by an appropriate support such as a silicone film and the manufacturing process is complicated. A plasma film or fibrin film prepared from human blood has excellent characteristics, but since the starting material is expensive, the film is not easily available. A film of a microbially-produced cellulose has problems in that the adhesion to epidermal cells is poor, the film is readily peeled from the wound to cause contamination, and regrowth of the skin is not promoted.